The 34-year-old made 27 Premier League appearances last season for the Cottagers.
Willian has re-signed for Fulham on a one-year deal with an option for a further 12 months.
The 34-year-old former Chelsea and Arsenal winger, holder of 70 Brazil caps, scored five goals and provided six assists in 27 Premier League appearances for the Cottagers last season as Marco Silva’s men finished 10th.
Having reached the end of his contract, Willian was understood to have been in talks with Nottingham Forest about a possible move and visited their training ground last week.
But he will again be with Fulham next season, saying in quotes on their official website: “I’m completely happy.
“Happy to sign one more year with Fulham. Happy to continue the work that I did last season with all my teammates and the whole club. I think it’s a club that can do even better this season, so I’m happy to continue this amazing adventure.”
Fulham owner Tony Khan said: “I’m thrilled that Willian will return to Fulham for at least one more season.
“He was a very important addition last summer and was a significant contributor during one of the most successful Premier League campaigns our club has ever had.
“We’re all very excited that he’ll return to Craven Cottage as we aim for another successful season in the Premier League together.”